摘要This study aimed to determine the effects of tributyrin on growth performance,gastrointestinal tract development,ruminal bacteria and volatile fatty acid(VFA)formation.Thirty healthy weaned Small-Tailed Han female lambs at 3 months old with BW 27.5±4.1 kg(mean±SD)were randomly assigned to five groups of six lambs each,and each group received tributyrin at 0,0.5,1.0,2.0 and 4.0 g/kg in feed.Weights were measured before the start and end of the study.After 15 d adaptation,DM1,feed,faeces and urine were recorded every week.Lambs were sacrificed at d 75.Compared to lambs fed no tribu-tyrin,lambs fed 4.0 g/kg tributyrin had higher average daily BW gain(P=0.04)and DMI(P＜0.01).Tributyrin reduced nitrogen(P＜0.01),Ca(P＜0.01)and P(P＜0.01)losses derived from faeces and urine.The mostly important,tributyrin increased dorsal sac thickness(P＜0.01),papillae length(P=0.04)and width(P＜0.01),ventral sac papillae length(P＜0.01)and width(P＜0.01),caudodorsal blind sac thickness(P=0.02),papillae length(P＜0.01)and width(P＜0.01).Furthermore,tributyrin increased thicknesses of both the duodenum(P＜0.01)and ileum(P=0.01),and villus heights of the duodenum(P=0.01),ileum(P＜0.01),jejunum(P＜0.01)and caecum(P=0.02),but tributyrin decreased duodenal(P＜0.01)and caecal crypt depths(P＜0.01).Tributyrin reduced rumen pH(P＜0.01)while promoting total VFA concentration(P＜0.01).Tributyrin improved the structure of rumen bacteria by enhancing Clostridium(P=0.04),Butyrivibrio(P＜0.01),Streptococcus(P=0.04),Prevotella(P=0.04),Ruminobacter(P=0.02)and Fibrobacter(P=0.03).In conclusion,tributyrin could stimulate gastrointestinal tract development by enhancing colonization of rumen VFA-producing bacteria,and dietary supplementation of tributyrin at 4.0 g/kg of DM was recommended for the weaned lambs.